Distributed Power Generation

Distributed Power Generation = an energy system (mainly) based on interconnected little and medium size power generators and/or renewable energy plants

(can also be understood as home production of solar energy)

Definition

Definition by Wikipedia at http://en.wikipedia.org/wiki/Distributed_generation

"Distributed generation generates electricity from many small energy sources. It has also been called also called on-site generation, dispersed generation, embedded generation, decentralized generation, Decentralized Energy or distributed energy." (http://en.wikipedia.org/wiki/Distributed_generation)

See also the Definition by Ezio Manzini at http://sustainable-everyday.net/manzini/?p=9

Description

Ezio Manzini:

"distributed power generation: This expression usually refers to an energy system (mainly) based on interconnected little and medium size power generators and/or renewable energy plants. Its implications is a radical change in the dominant idea of electrical system. But not only: there is the possibility of a new relationship between communities and their technological assets and, possibly, a more democratic way of managing the energy system.

Today, even if it is not yet the main stream strategy, the option of the distributed generation is largely recognized as a very promising one and its implementation has been enhanced in several different contexts, both in dense urban spaces and in the country side, in the North and in the south of the world. The distributed power option has been made possible thanks to the convergence of several factors as: the existence of highly effective little and medium size power generators and the possibility to base the new energy systems on an intelligent information network." (http://sustainable-everyday.net/manzini/?p=9)

Discussion

New Rules website:

"In the early 20th century electricity generation and transmission technologies supported the idea that "big is better." As a result, regulatory rules encouraged the construction of centralized power plants and long distribution lines. In the 1990s the technological dynamic was reversed. Small power plants located closer to the customer were become increasingly competitive. This has occurred at the same time as most states, many cities, and the U.S. Congress are rewriting the rules that govern our electricity system. The challenge now is to write rules (i.e. codes, standards, regulations, statutes) that will encourage electricity customers to also become electricity producers." (http://www.newrules.org/electricity/producers.html)

Wikipedia:

"Distributed generation is another approach. It reduces the amount of energy lost in transmitting electricity because the electricity is generated very near where it is used, perhaps even in the same building. This also reduces the size and number of power lines that must be constructed.

Typical distributed power sources have low maintenance, low pollution and high efficiencies. In the past, these traits required dedicated operating engineers, and large, complex plants to pay their salaries and reduce pollution. However, modern embedded systems can provide these traits with automated operation and clean fuels, such as sunlight, wind and natural gas. This reduces the size of power plant that can show a profit.

The usual problem with distributed generators are their high costs." (http://en.wikipedia.org/wiki/Distributed_generation)

Policy Implications

"In the era of electric deregulation customers have the ability to choose their electric supplier. But early indications are that the vast majority of consumers will choose not to choose. Who, then, should be their default supplier? In most states the incumbent utility has been given this huge pot of customers--only Massachusetts and Ohio have thus far decided that it should be the town or city who is responsible for serving these customers.

Community choice, or aggregation, will create community pools of electricity large enough to command leverage on the market, and with sufficient legal authority and financial flexibility to demand contracts from energy suppliers that satisfy local economic and environmental goals. In short, it places authority in the hands of those who will feel the impact of their decisions, making investment in renewable electricity much more likely." (http://www.newrules.org/electricity/default.html)

Examples

From the Wikipedia:

"The one exception is probably microhydropower. A well-designed plant has nearly zero maintenance costs, and generates useful power indefinitely.

One favored source is solar panels on the roofs of buildings. These have high construction costs ($2.50/w, 2007). This is about fifty-fold higher than coal power plants ($0.047/w, 2007) and 40-fold higher than nuclear plants ($0.06/w, 2007). Most solar cells also have waste disposal issues, since solar cells often contain heavy-metal electronic wastes. The plus side is that unlike coal and hydropower, there are no pollution, mining safety or operating safety issues.

Another favored source is small wind turbines. These have low maintenance, and low pollution. Construction costs and total safety are also manyfold ($0.80/w, 2007) less per watt than large power plants, except in very windy areas. Wind towers and generators have substantial insurable liabilities caused by high winds, but good operating safety.

Distributed cogeneration sources use natural gas-fired microturbines or reciprocating engines to turn generators. The hot exhaust is then used for space or water heating, or to drive an absorptive chiller for air-conditioning. The clean fuel has only low pollution. Designs currently have uneven reliability, with some makes having excellent maintenance costs, and others being unacceptable.

Cogenerators are also more expensive per watt than central generators. They find favor because most buildings already burn fuels, and the cogeneration can extract more value from the fuel.

Some larger installations utilize combined cycle generation. Usually this consists of a gas turbine whose exhaust boils water for a steam turbine in a Rankine cycle. The condenser of the steam cycle provides the heat for space heating or an absorptive chiller. Combined cycle plants with cogeneration have the highest known thermal efficiencies, often exceeding 85%." (http://en.wikipedia.org/wiki/Distributed_generation)

More Information

When consumers become producers, at http://www.newrules.org/electricity/producers.html . This site monitors regulatory progress in the U.S.

Local and regional plans update, at http://www.newrules.org/electricity/planningfordg.html

See our entry on the P2P Energy Grid